Method of precipitating salt.



J. HODGKINSON. METHOD 0F PRECIPITATING SALT. APPLIUATION FILED Amm,1910. RBNBWED JAN. 18, 1913.

Patented June 17, 1913.

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UNITED STATES PATENT OEEIC.,

JAMES HODG-KINSON, 0F MANCHESTER, ENG-LAND, ASSIGNOR TO JAMES FRANCISVSEACOMBE, OF EAST'I-IAM, ESSEX, ENGLAND.

METHOD OF PRECIPITATING SALT.

Specification of Letters Patent.

Patented June 1 7, i913.

Application filed April 1, 1910, Serial No; 552,938. Renewed January 18,1913. Serial No. 742,977.

To all whom it may concern .f

Be it known that I, JAMESITIODGKINSON, a subject of the King of GreatBritain, and resident of Manchester, county of Lancaster, England, haveinvented certain new and useful Improvements in New and Improved Methodsof Precipitating Salt, of which the following is a specification.

My invention hereinafter described relates to the evaporation of brinefor the production of common salt, by heat artificially applied.I-Ieretofore this evaporation has largely been produced by What iscalled the vacuum system, Which is effective but expensive by reason ofthe complication and cost of the plant, and also by reason of the costof the fuel required.

In the manufacture of salt by evaporation I have found that it isessential for the production of ne salt, such as that required for tableuse, to' heat the brine to a very high temperature, since the finenessof the crystals depends upon the high temperature. Further, and becausethe size of the crystals depends upon the temperature, it is essentialfor uniformity of size of crystals, that there should be uniformity oftemperature in the heat applied to the evaporating pan, and this heatshould not vary more than tivo or three degre-es during the process ofproduction of a given amount or charge. This uniformity of heat appliedto the evaporating pans may be approximated by the use of steam, butthis requires apparatus for the generation of steam, which is merely, inthis case, a conveyer of heat, Wit-h the Waste of coal incident alwaysto the generation of steam. Furthermore, it is desirable to producedifferent grades of salt of uniform grain, Without grinding, and this Ihave accomplished by subject-ing successive pans to a relatively highand uniformly maintained heat, though lower than that maintained in theprimary pan. I have accomplished all these desired results in myinvent-ion by a simple process which involves only a simple apparatusand a greatly lessened expenditure of fuel.

The essential point in my said invention therefore is the application ofa closely and uniformly regulated high heat to the evaporating pans,Which contain an amount of brine held therein and subjected to thisuniform heat during the process of crystallization. I use, as apreferred means for .gen-

erating this heat, a furnace fed by a stoler, such as that shown in myUnited States patent of October 29/07, #869.798, this furnace consumingcoal fed in regulated quantities andy Without material variation in theheat generated. t is arranged in such relation to the first pan as togive its full heat theretoy and to raise the heat of the first pan ashigh asV 1800O E., this temperature being sometimes used in actualpractice. To have practical and economical use, the heat of the productsof combustion is further utilized by being conveyed to other pansarranged in succession, the heat thus applied to the successive pansbeing' of course diminished regularly but still remaining uniform foreach pan to Which it is applied and by this method different grades ofsalt varying in the size of the crystals, such as butter salt and fishsalt are produced by the heat of the same furnace. In order to secure ahigh heat, however, in the firstpan it is necessary that this pan shouldbe covered, steam being led from it under proper regula-tion, andutilized to heat the next pan in order, if desired, or for otherpurposes. The second pan may have a false bottom or acket forming asteam chamber through Which the steam from the first pan is conducted.Preferably, as hereinafter shown, this steam chamber occupies the bottomof the second pan and a part of the side Wall. The second pan or panstherefore may receive the heat of the products of combustion which havepassed the first pan and also the steam from the first pan so that theWhole of the heat is utilized. I may have one or more secondary pans andmay .continue the operation of utilizing the heat of the products ofcombustion with or Without the steam by extending the series tootherpans either closed or open. I thus obtain in the first pan with itsuniformly maintained, high heat, the finest grade of salt, useful fortable salt and the like Without grinding, a thing never beforeaccomplished so far as I am aware, and in the succeeding pans coarserand still coarser grades of salt, all these .grades being uniformbecause of the uniform heat applied to each pan, thus preventingprecipitation of crystals of irregular size.

In order that the method may be better understood, I show in theaccompanying drawings enough of the apparatus disclosed in a formerapplication for this purpose.

In these drawings, Figure l is an entire diagrammatic plan showing theprimary and secondary pans and the heating means. Fig. 2 shows a.longitudinal section following the construction of the plant shown inFig. l. F ig. 8 shows7 detached, a pan having a false bottom or aclretforming a steam chamber.

In this apparatus is a primary pan A clised as shown at a, and providedwith suitable means for supplying brine thereto. This pan is suitablyset in briclr worlr and has flue passages for the products of combustionunderneath, preferably with baffles. I prefer to first heat the brineand then pass it tl'irough coils o which are in the path of the productsof combustion, and from these coils the brine passes to the pans throughpipe c. The products of combustion as shown in Figs. l and 2 passdirectly from the furnace c underneath the lirst pan and from thence topans A, A2, and after leaving these pans may pass beneath other panseither closed or open. Dampers or valves divert. a part or the whole ofthe flue gases from the primary to either of t-he secondary pans orallow an equal flow of heat to each.

The number of pans is not material but it desirable in the interest ofeconomy of fuel to utilize all the heat units in the products ofcombustion.

I iind it preferable to maintain the heat of the first pan not. lowerthan 1.0000 F., but I do not limit myself as to the ranges oftemperature. excepting that the temperature must be practically uniformat each stage to secure a uniform. product and must be abnormally highin the first pan to obtain crystals of such lineness as to be used astable salt without subsequent grinding. By ab` normal heat I mean atemperature between 1000D F. and 18000 Il. but whatever the tem peratureis at the beginning it must be lrept uniform throughout the operation.

Figs. l and 2 show the pans heated by the products of combustion fromfurnace c but in IP ig. -l I conduct the steam generated in the firstpan to the secondary pans which are provided with a jaclretedevaporator, and in such case the steam would enter at u and leave at u',u2 being a drainage outlet. The steam generated within the evaporatorwould pass through outlet pipe n3 to be utilized as might be desired.

Illhat I claim as my invention is l, rlhe method herein described ofproducing a line quality of salt by direct precipitation and withoutgrinding, consisting in subjecting the brine in a closed pan to anabnormally high temperature uniformly maintained, substantially asdescribed.

2. rIhe herein described method of evaporating brine to forni salt,consisting in subjecting the brine in a closed pan to an abnormally hightemperature uniformly maintained, and in conducting theheat from thefirst pan to a second pan and maintaining the heat at a uniform hightemperature but lower than that in the lirst pan so as to obtain aprecipitation of crystals of a different grade from that in the firstpan, substantially as described.

3. The herein described method of evaporating brine to form saltconsisting in subjectin the brine in a closed pan to the products ofcombustion of a uniformly regulated furnace, and in conducting theproducts of combustion and the steam of the first pan to a second pan orpans, substantially as described.

el. The method herein described of treat-- ing brine for the productionof salt consisting' in subjecting the brine held in a series of closedpans to the products of combustion of a uniformly regulated furnaceapplied to the series in succession and in conducting the steam from theclosed pans in succession from each to the next throughout the series,substantially as described.

In testimony whereof, I afllix my signature in presence of twowitnesses.

JrltlllllS IIODGKINSON. lllitnesses BENNETT S. Jonas, FRANK I. DANroRD.

Copies of this patent may be obtained 'for five cents each, by adressngthe Commissioner of Patents,

Washington, D. C.

